Respiratory diseases, such as, tuberculosis, are of critical concern to hospitals or long term care medical facilities, particularly as it may adversely affect medical personnel therein. Since existing medical facilities are often not well equipped for isolating patients with infectious respiratory diseases, the risk to the healthcare worker and others because of the presence of pathogens in the air is very high. The Centers for Disease Control (CDC) in Atlanta, Ga. has proposed guidelines, e.g., published as Guidelines for Preventing the Transmission of Tuberculosis in Health-Care Facilities, 1993, Second Edition, for medical facilities, for emergency rooms, isolation rooms, etc. Such guidelines, however, address only the dilution of air in an entire room after the pathogens have already mixed with the existing room and hospital air. Even under such guidelines, health care workers are still at relatively high risk of exposure to the airborne pathogens.
Various portable patient isolation rooms and air filtering systems have been developed for either isolating patients or filtering the overall room air. For example, U.S. Pat. No. 5,074,894 issued on Dec. 24, 1991 to T. P. Nelson describes an enclosure which can be assembled to entirely enclose a patient within an ordinary hospital room. However, such enclosures are bulky, expensive and require some skill to assemble and, hence, are not of great practical use.
Moreover, other systems designed to withdraw patient generated contaminants from a room utilize one or more air inlets positioned at one or more locations generally remote from the patient or patients in the room so that such air throughout the entire room is withdrawn and air localized at a particular patient can not be captured before it is by health-care personnel who are present in the room.
Further, the proposed Centers for Disease Control Guidelines specifically state: "Source control techniques can prevent or reduce the spread of infectious droplet nuclei into the general air circulation. These techniques are called source control methods because they entrap infectious droplet nuclei as they are emitted by the patient, or source . . . Local exhaust is the preferred ventilation technique. Because local ventilation captures airborne contaminants very near their source, before they can disperse, it is often the most efficient way to contain contaminants." Thus, it is desirable to prevent the general dispersion into a room or other enclosed space of patient generated airborne pathogens, such as tuberculosis, when the patient is laying or sitting on his or her hospital bed. However, no effective source control techniques are currently available to the art.